X-ray multilayers are key optical elements in synchrotron radiation and free electron laser facilities， astronomical observations， plasma diagnostics， and lab-based analytical instruments. They can realize highly efficient reflection， monochromatization， and polarization of X-rays. Our group has been conducting systematic studies on the design， fabrication， and characterization of X-ray multilayers during the past 20 years. We have developed a series of high-performance multilayers with world-class level reflectivity at different wavelengths and have built the deposition platform for large size X-ray multilayers based on the magnetron sputtering technique. The largest deposition mirror could achieve a length of 1.2 m. The fabricated， hard X-ray multilayer mirrors have been successfully applied in synchrotron radiation facilities both in China and abroad. Through the combination of multilayer and reflective gratings， innovative， ultrahigh efficiency， tender， X-ray multilayer grating optics have been developed. Compared with conventional single-layer gratings， a maximum efficiency improvement of 40 times could be achieved. This study will introduce the results and progress that were achieved by our group in X-ray multilayer elements.